If someone becomes successful in sports betting over the long run, would you say that’s because of luck or skill?
Skills but won't be possible without luck. There are 2 kinds of gambling games, the skill and the luck-based (but still both need luck). If you play luck-based, your chances to win entirely relying on luck. But in skill-based (like sports betting) knowledge is your edge. Because you're not just placing bets blindly, you're using your knowledge in order to maximize the chance to get a good result.
Therefore, it's not just about your luck
but your, having a knowledge on the specific game
is a plus point. If a gambler became profitable as a bettor in the long run then we can say it's because of
hisboth skills and luck that's why it made possible.